Vacuum assisted ply placement shoe and method

ABSTRACT

A device for placing a ply on a substrate surface includes a vacuum manifold assembly configured for attachment to a vacuum source and a substrate seal configured to provide a substantially gas impermeable interface with the substrate surface. This device further includes a ply seal configured to provide a substantially gas impermeable interface with the ply. In this manner, vacuum applied to the vacuum manifold assembly depressurizes an area between the ply and the substrate surface.

FIELD OF THE INVENTION

[0001] The present invention generally relates to a ply placementdevice. More particularly, the present invention pertains to a vacuumassisted ply placement device.

BACKGROUND OF THE INVENTION

[0002] Laminated materials such as, for example, composites are widelyutilized to increase structural rigidity in a wide variety of products.For example, composites are generally utilized by the airplaneconstruction industry to build structural members of airframes. In someof the most advanced aircraft, where high strength and rigidity and lowweight are extremely important, composites may account for a significantportion of the airframe as well as the external surface or skin.Typically, these composites are constructed from a plurality of layersplaced over a form. These layers are often referred to as partial orfull plies. For structures exceeding the available material width, eachlayer is typically made up of a series of strips or courses of materialplaced edge to edge next to each other. Each ply may be in the form ofwoven fibers in a fabric, unidirectional fiber material or a variety ofother conformations. Unidirectional fiber material is often termed,“tape.” The fibers may be made from any of a multitude of natural and/or“man-made” materials such as fiberglass, graphite, Kevlar®, and thelike.

[0003] While these plies may simply include the above described fibers,generally the plies are pre-impregnated with a resin. Resins aretypically formulated to allow the ply to adhere to the form as well asto previously applied plies. If some plies do not adequately adhere totheir respective substrate, such as the previously applied plies or theform, internal and/or external surface imperfections. Accordingly, inorder to facilitate proper adhesion, pressure is typically applied tothe plies during and/or after ply placement.

[0004] For relatively small items, a press may be employed. For example,some known presses utilize a vacuum debulking table. In sucharrangements, following placement of the plies, the part, referred to asa layup, is placed on the debulking table, a membrane is placed over thelayup, and a pump is employed to remove the air from the layup. As thelayup is depressurized, a compressive force is applied by theatmospheric pressure and air within the layup is removed. However, asthe size of the layup increases and/or permeability of the layupdecreases, the use of debulking tables tends to become undesirablyexpensive and cumbersome.

[0005] For relatively larger items, a rolling press may be employed. Forexample, in some known rolling presses, tape is dispensed from adispensing head and then pressed on the substrate surface with acompaction roller. While the exact amount of force exerted by the rollerdepends upon a variety of factors, 100 Kg or more is often utilized incertain applications. In order to exert this relatively large forcewhile accurately placing plies, substantial support and guidancestructures are generally required. Another disadvantage of such knownrolling presses is that a correspondingly substantial support isrequired for the form in order to withstand the force exerted by theroller. These and other disadvantages associated with the relativelylarge forces employed by rolling press systems greatly increase thecosts of producing composite items.

[0006] Accordingly, it is desirable to provide a method and apparatuscapable of overcoming the disadvantages described herein at least tosome extent.

SUMMARY OF THE INVENTION

[0007] The foregoing needs are met, to a great extent, by the presentinvention, wherein in one respect an apparatus and method is providedthat in some embodiments accurately place plies and generate sufficientforce to facilitate proper adhesion of the plies to the substrate.

[0008] In accordance with an embodiment of the present invention, adevice for placing a ply on a substrate surface includes a vacuummanifold assembly configured for attachment to a vacuum source and asubstrate seal configured to provide a substantially gas impermeableinterface with the substrate surface. This device further includes a plyseal configured to provide a substantially gas impermeable interfacewith the ply. In this manner, vacuum applied to the vacuum manifoldassembly depressurizes an area between the ply and the substratesurface.

[0009] In accordance with another embodiment of the present invention, asystem for placing a ply or a substrate surface includes a vacuumassisted ply placement device configured to apply a ply on a substratesurface. This ply placement device includes a vacuum manifold assemblyconfigured for attachment to a vacuum source and a substrate sealconfigured to provide a substantially gas impermeable interface with thesubstrate surface. This ply placement device further includes a ply sealconfigured to provide a substantially gas impermeable interface with theply. In this manner, vacuum applied to the vacuum manifold assemblydepressurizes an area between the ply and the substrate surface. Thesystem for placing the ply further includes a control system thatcontrols movement of the ply placement device relative to the substrate.Thus, the ply is dispensed from the ply placement device in response tothe movement of the ply placement device relative to the substrate.

[0010] In accordance with yet another embodiment of the presentinvention, a method of producing a composite structure includes steps ofpreparing a layup form having a substrate surface configured to receivea ply and introducing a vacuum assisted ply placement device to thesubstrate surface. The method further includes applying the ply to thesubstrate surface to

[0011] In accordance with yet again another embodiment of the presentinvention, an apparatus for producing a composite structure includes ameans for preparing a layup form means having a substrate surfaceconfigured to receive a ply means and a means for introducing a vacuumassisted ply placement device to the substrate surface. The apparatusfurther includes a means for applying the ply means to the substratesurface to produce the composite structure and a means for curing thecomposite structure.

[0012] There has thus been outlined, rather broadly, certain embodimentsof the invention in order that the detailed description thereof hereinmay be better understood, and in order that the present contribution tothe art may be better appreciated. There are, of course, additionalembodiments of the invention that will be described below and which willform the subject matter of the claims appended hereto.

[0013] In this respect, before explaining at least one embodiment of theinvention in detail, it is to be understood that the invention is notlimited in its application to the details of construction and to thearrangements of the components set forth in the following description orillustrated in the drawings. The invention is capable of embodiments inaddition to those described and of being practiced and carried out invarious ways. Also, it is to be understood that the phraseology andterminology employed herein, as well as the abstract, are for thepurpose of description and should not be regarded as limiting.

[0014] As such, those skilled in the art will appreciate that theconception upon which this disclosure is based may readily be utilizedas a basis for the designing of other structures, methods and systemsfor carrying out the several purposes of the present invention. It isimportant, therefore, that the claims be regarded as including suchequivalent constructions

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]FIG. 1 is a cutaway view of a ply placement device according to anembodiment of the invention.

[0016]FIG. 2 is a perspective view of the ply placement device of FIG.1.

[0017]FIG. 3 illustrates an exemplary dispensing head according to anembodiment of the invention.

[0018]FIG. 4 illustrates an exemplary ply placement system according toan embodiment of the invention.

[0019]FIG. 5 is a flowchart illustrating steps that maybe followed inaccordance with an embodiment of the method or process.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0020] The present invention provides a ply placement device and method.In some embodiments, the ply placement device includes a vacuum manifoldassembly configured for attachment to a vacuum source and a substrateseal configured to provide a substantially gas impermeable slidinginterface with a substrate surface, such as the surface of a layup form,the surface of previously placed plies, and any other surface on towhich the ply may be placed. The ply placement device also includes aply seal configured to provide a substantially gas impermeable slidinginterface with the ply. Vacuum applied to the vacuum manifold assemblydepressurizes an area between the ply and the substrate surface.

[0021] Another embodiment in accordance with the present inventionprovides a method of producing a composite structure. A layup formcorresponding to the composite structure and having a substrate surfaceconfigured to receive a ply is prepared. A vacuum assisted ply surfaceto produce the composite structure. The composite structure is cured tobind the multiple plies of the composite product together to generate astrong, cohesive structure.

[0022] Advantages of various embodiments of the invention include: (1)reduce the load to be exerted by the support and guidance structures;(2) reduce the load on the layup form by the ply placement system; (3)increased duration of force pressing the ply on the substrate; (4)decreasing occurrences of air pockets between placed plies and substrate(layup form and/or substrate plies); and (5) ability to utilizerelatively wider ply material.

[0023] The invention will now be described with reference to the drawingfigures, in which like reference numerals refer to like partsthroughout. As shown in FIG. 1, a vacuum assisted ply placement device10 (“VAPPS”) is configured to place and apply a ply 12 on a substrate14. The VAPPS 10 includes a vacuum manifold 16, a lower seal 18, anupper bridge 20, and an upper seal 22. The lower seal 18 is configuredto bear against the substrate 14 and form a substantially gasimpermeable interface between the lower seal 18 and the substrate 14. Inaddition, as a result of the action of the lower seal 18 pressing uponthe substrate 14, the upper seal 22 is caused to bear against the ply 12and press the ply 12 against the upper bridge 20. In this manner, asubstantially gas impermeable interface between the upper seal 22 andthe ply 12 may be formed. Furthermore, in various embodiments of theinvention, the ply 12 or, more preferably, a backing 24 on the ply 12 isconfigured to be substantially gas impermeable.

[0024] The vacuum manifold 16 may be attached to a vacuum source by, forexample, a vacuum hose 26 in any suitable manner. The vacuum manifold 16includes one or more channels 28 configured to connect the vacuummanifold 16 to an area at, or near, a trailing tip 30 of the VAPPS 10.

[0025] As illustrated in FIG. 2, a side plate 32 is attached to eachside of the VAPPS 10. These side plates 32 are configured to essentiallyseal the side edges of the lower seal 18 and the upper seal 22. Inaddition, the side plates 32 are configured to bear against therespective edges and the respective side plates 32. Furthermore, theside plates 32 include a bottom edge 34 configured bear against thesubstrate 14 to form a substantially gas impermeable interface betweenthe substrate 14 and the respective bottom edges 34. Together, thebottom edges 34 and the lower seal 18 form a substrate seal configuredto provide a substantially gas impermeable interface with the surface ofthe substrate 14. This substrate seal is maintained as the VAPPS 10 ismoved and slides relative to the substrate 14 as described herein.Moreover, the side plates 32 in combination with the upper seal 22 forma ply seal configured to provide a substantially gas impermeableinterface with the ply 12 and/or the backing 24. This ply seal ismaintained as the ply 12 is drawn out of the VAPPS 10 as describedherein below.

[0026] In operation, the VAPPS 10 is moved the in the direction shown byarrow A relative to the substrate 14. As gas, for example air, isremoved from the trailing tip 30, a depressurized area is formed betweenthe substrate 14 and the backing 24 and/or the ply 12. As the VAPPS 10continues to move in direction A relative to the substrate 14, the ply12 is drawn towards the substrate 14. Prior to the relative movement ofthe VAPPS 10 to the substrate 14, an end of the ply 12 extending fromthe VAPPS 10 is attached to the substrate 14 by the action of a sweep 36pressing the ply 12 against the substrate 14. This process is oftenreferred to as “tacking.” Thereafter, as the VAPPS 10 is moved relativeto the substrate 14, the ply 12 is caused to be drawn out of the VAPPS10.

[0027] Depending on the strength of the vacuum source and/or the levelof regulated vacuum applied, a result of the depressurization betweenthe substrate 14 and the ply 12 and/or the backing 24, the ply 12 ispressed unto the substrate 14 with a force [“fat”] approaching ambientatmospheric pressure. Depending upon the permeability of the backing 24,the ply 12, and the substrate 14, the fat may continue to consolidatethe ply 12 and/or the substrate 14 for approximately several seconds.The elapsed time interval of pressure provides the ability of the ply 12to form a relatively stronger bond with the substrate 14, thanconventional ply placement

[0028] The VAPPS 10 further includes a connector 38 configured to attachthe VAPPS 10 to a dispensing head, as seen in FIG. 3. In variousembodiments of the invention, the connector 38 may be configured toprovide pivotal, retractable, and/or essentially rigid attachment to thedispensing head. Preferably pivotal movement of the VAPPS 10 relative tothe dispensing head may occur in more than one axis at a time and may becontrolled by any suitable means.

[0029] As shown in FIG. 3, a dispensing head 40 suitable for use in anembodiment of the invention includes a material feeder 42, a cuttingassembly 44, a heater assembly 46, and sensor 48. The material feeder 42is configured to control the movement of the ply 12 into the VAPPS 10during various stages of ply placement. For example, the material feeder42 may include a plurality of rollers 50 configured to engage the ply 12and controlled to rotate via the action of a motor 52. In addition, thematerial feeder 42 is configured to disengage the rollers 50 to allowthe ply 12 to move freely.

[0030] The cutting assembly 44 is configured to cut the ply 12 and/orthe backing 24 in a controlled manner. The cutting assembly 44 mayemploy any known cutting device such as various bladed devices, lasers,and the like. In a specific example, the cutting assembly 44 includes anultrasonic knife 54 controlled to rotate by the action of a motor 56.The ultrasonic knife 54 is further controlled to traverse the full widthof the ply 12 or any portion thereof by the action of a motor 58configured to rotate a jackscrew 60.

[0031] When utilizing specific materials and/or operating conditions inwhich heating of the material is advantageous, the heater assembly 46 isconfigured to impart thermal energy upon the ply 12. In this regard, anyknown device operable to heat the ply 12 in a suitable manner may beutilized by various embodiments of the invention. For example, theheater assembly 46 may include a diverter valve 62 configured to controlthe flow of heated air directed onto the ply 12.

[0032] The sensor 48 is configured to sense the ply 12. For example, thesensor 48 may the sensor 48 may be configured to sense the ply 12 beingplaced by the dispensing head 40. In addition, the sensor 48 may sense apreviously placed ply 12. In this manner, the position of the ply 12being placed relative to the previously placed ply 12 may be determined.The sensor 48 and/or other sensors may also be utilized for flawdetection, material tension, material utilization, and the like.Furthermore, the sensor 48 and/or other sensors may be operable to senseattributes of underlying substrate 14 such as density, thickness, andthe like.

[0033] As shown in FIG. 4, a gantry-type, automated tape laying device[“ATLD”] 64 suitable for use in an embodiment of the invention includesa gantry 66, the dispensing head 40, and a form 68. The gantry 66 isconfigured to control the movement of the dispensing head 40. In anembodiment of the invention, the gantry 66 is configured to control tenaxis of movement (five axis of the gantry and five axis of thedispensing head 40). However, it is to be understood that the specificnumber of axis may depend upon the particular operating condition andthus, the number of axis controlled is not critical to the invention. Abenefit of various embodiments of the invention is that the gantry 66need not be configured to impart the force of a compaction roller uponthe layup and form. Thus, the gantry 66 may be relatively lighter andless rigid than conventional automated tape laying devices. The form 68is configured to provide a suitably stable surface for ply placement. Itis another benefit of various embodiments of the invention is that theform 68 need not be configured to withstand the force of a compactionroller.

[0034]FIG. 5 illustrates steps involved in a method 70 of placing pliesto produce a composite structure or product. Prior to the initiation ofthe method 70, a composite product is designed and a series of computerreadable instructions specifying attributes of the composite product isgenerated. These instructions are utilized to control the operations ofthe ATLD 64 and construct a form such as the form 68. This form isfurther positioned within the operational area of the ATLD 64.

[0035] At step 72, the method 70 is initiated by turning on the variouscomponents of the

[0036] At step 74, the ply 12 is advanced by the action of the materialfeeder 42. For example, the rollers 50 may engage the ply 12 and advancethe ply through the VAPPS 10 until the ply 12 is positioned to beapplied to the substrate 14, referred to as being tacked. To ensure theply 12 has advanced a suitable amount, the sensor 48 may be utilized tosense the position of the ply 12. In addition, the location on the form68 is determined based upon the series of computer readable instructionand/or the location of a previously positioned ply 12. Furthermore,prior to tacking the ply 12 to the substrate at step 76, the end of theply 12 may be cut based upon the series of computer readableinstruction, the orientation of a previously positioned ply 12, and/orthe location of a previously positioned ply 12. Following step 74, therollers 50 may disengage the ply 12 to allow for unimpeded dispensing ofthe ply 12.

[0037] At step 76, the ply 12 is tacked to the substrate. In anembodiment of the invention, the ply 12 is tacked by positioning theVAPPS 10 with the ATLD 64 such that the sweep 36 is controlled to pressthe ply 12 on to the substrate with sufficient force so as to cause theply 12 to adhere to the substrate. In addition, the lower seal 18 andthe bottom edges 34 are controlled to contact the substrate 14. In thismanner, as air is withdrawn via the vacuum manifold 16 and adepressurized area is formed at the trailing tip 30.

[0038] At step 78, the ply 12 is dispensed along a path across the form68. In order to minimize deformations in the ply 12 (e.g., wrinkles),this path is typically calculated to coincide with a “natural path”based upon any contours in the form 68. As the dispensing head 40 iscontrolled along the path across the form 68, any leakage of air intothe depressurized area is removed from the trailing tip 30 by the actionof the vacuum source. In this manner, the depressurized area ismaintained between the substrate 14 and the backing 24 and/or the ply12. This depressurized area is defined by the boundaries created by theseals 18 and 22, the bottom edges 34 of the side plates 32, thesubstrate 14, and the backing 24 and/or the ply 12. As the dispensinghead 40 moves along the path, the ply 12 is drawn out of the dispensinghead 40 and moves along the path, a section of the ply 12 is drawn outof the dispensing head to a point in which support provided by the upperseal 22 is no longer sufficient to withstand the fat and maintain aseparation of the ply 12 from the substrate 14. Thus, this section ofthe ply 12 is pressed on to the substrate 14.

[0039] An advantage various embodiments of the invention as compared toknown ply placement devices is a relatively extended duration pressureis applied to the ply 12. This extended duration increases thelikelihood the ply 12 will adequately adhere to the substrate 14. Afurther benefit is that due to the removal of air between the ply 12 andthe substrate 14, the occurrence of air pockets or voids is reduced ascompared to known ply placement devices.

[0040] At step 80, the placement of the ply 12 on the substrate 14 isevaluated. For example, the sensor 48 may sense the relative position ofthe ply 12 and a previously positioned ply 12 and determine if thedistance between these plies is within a predetermined tolerance. If thedistance between these plies is not within the predetermined tolerance,an error may be generated at step 82. If the distance between theseplies is within the predetermined tolerance, it is determined if the endof the path has been reached at step 84.

[0041] At step 84, it is determined if the end of the path has beenreached. If, based on the series of computer readable instruction, it isdetermined the dispensing head 40 has not advanced to the end of thepath, additional ply 12 is dispensed at step 78. If, it is determinedthe dispensing head 40 has advanced to the end of the path, the ply 12is cut at step 86.

[0042] At step 86, the end of the ply 12 may be cut based upon theseries of computer readable instruction, the orientation of a previouslypositioned ply 12, and/or the location of a previously positioned ply12. Optionally, if the ply 12 includes a backing 24, this backing 24 maybe removed prior to placing another ply 12. This backing 24 may beremoved by an automated take-up device positioned on the dispensing head40 by an operator, or any other

[0043] At step 88, it is determined if the placement of plies 12 on thecomposite product has been completed. For example, if all of thecomputer readable instructions have been completed, it may be determinedthat the placement of plies for the composite product has been completedand the ATLD 64 may idle until another series of computer readableinstructions is initiated. If is determined the placement of plies 12for the composite product is not completed, an additional ply 12placement may proceed at step 74.

[0044] Following the method 70, the composite product may be cured inany suitable manner. In the aerospace industry, thermoset resins aregenerally utilized to pre-impregnate ply material. These thermosetresins are typically cured by being held at an elevated temperature fora predetermined amount of time. Times and temperatures may be selecteddepending on the resin used, the size and thickness of the compositeproduct, and the like. An advantage of at least some embodiments of theinvention is that the utilization of vacuum assisted ply placementallows for the use of relatively wider ply 12. In known ply placementsystems, wider ply stock necessitates the use of longer compactionrollers and thus greater force on the compaction rollers to achieveadequate kilograms per centimeters (“Kg/cm²”) load across the ply.

[0045] Although an example of the VAPPS 10 is shown being controlled bythe gantry 66, it will be appreciated that other control systems can beused. In this regard, it is an advantage of embodiments of the inventionover known ply placement devices that support and control structures canbe made lighter due to the elimination of the compaction roller. Also,although the VAPPS 10 is useful to place plies for composite products inthe airline industry it can also be used in other industries thatconstruct composite product. These industries include, but are notlimited to, automobile, marine, spacecraft, building, and consumerproducts.

[0046] The many features and advantages of the invention are apparentfrom the detailed specification, and thus, it is intended by theappended claims to cover all such features and advantages of theinvention which fall within the true spirit and scope of the invention.Further, desired to limit the invention to the exact construction andoperation illustrated and described, and accordingly, all suitablemodifications and equivalents may be resorted to, falling within the

What is claimed is:
 1. A device for placing a ply on a substratesurface, comprising: a vacuum manifold assembly configured forattachment to a vacuum source; a substrate seal configured to provide asubstantially gas impermeable interface with the substrate surface; anda ply seal configured to provide a substantially gas impermeableinterface with the ply, wherein vacuum applied to the vacuum manifoldassembly depressurizes an area between the ply and the substratesurface.
 2. The ply placement device of claim 1, further comprising acutter configured to cut the ply.
 3. The ply placement device of claim1, further comprising a heater configured to apply heat to the ply. 4.The ply placement device of claim 1, further comprising at least onesensor configured to sense a condition of the ply.
 5. The ply placementdevice of claim 4, wherein the at least one sensor includes an opticalsensor.
 6. The ply placement device of claim 4, wherein the at least onesensor includes a sensor configured to locate an edge of a previouslyapplied ply.
 7. The ply placement device of claim 1, wherein thesubstrate seal is configured to substantially conform to a surface ofthe substrate.
 8. A system for placing a ply or a substrate surfacecomprising: a vacuum assisted ply placement device configured to apply aply on a substrate surface, comprising: a vacuum manifold assemblyconfigured for attachment to a vacuum source; a substrate sealconfigured to provide a substantially gas impermeable interface with thesubstrate surface; and a ply seal configured to provide a substantiallygas impermeable interface with the ply, wherein vacuum applied to thevacuum manifold assembly depressurizes an area between the ply and thesubstrate surface; and a control system that controls movement of theply placement device relative to the substrate, wherein the ply isdispensed from the ply placement device in response to the movement ofthe ply placement device relative to the substrate.
 9. The ply placementsystem of claim 8, further comprising a reel for supporting a supply ofthe ply.
 10. The ply placement system of claim 8, wherein the substrateseal is configured to conform to a curvature of a surface of thesubstrate.
 11. The ply placement system of claim 8, wherein the plyplacement device is pivotally attached to the control system, wherebythe ply placement device is configured to follow a contour of thesubstrate.
 12. The ply placement system of claim 8, further comprising acutter for cutting the ply.
 13. The ply placement system of claim 8,further comprising a heater for applying heat to the ply.
 14. The plyplacement system of claim 8, further comprising at least one sensor forsensing a condition of the ply.
 15. The ply placement system of claim14, wherein the at least one sensor includes an optical sensor.
 16. Theply placement system of claim 14, wherein the at least one sensorincludes means for locating an edge of a previously applied ply.
 17. Amethod of producing a composite structure, comprising: preparing a layupform having a substrate surface configured to receive a ply; introducinga vacuum assisted ply placement device to the substrate surface;applying the ply to the substrate surface to produce the compositestructure; and curing the composite structure.
 18. The method of claim17, further comprising tacking a first end of the ply to the substratesurface.
 19. The method of claim 17, further comprising sensing acondition of the applied ply.
 20. The method of claim 19, furthercomprising determining whether the applied ply is placed within apredetermined location based on the sensing.
 21. The method of claim 17,further comprising cutting the ply.
 22. An apparatus for producing acomposite structure, comprising: means for preparing a layup form meanshaving a substrate surface configured to receive a ply means; means forintroducing a vacuum assisted ply placement device to the substratesurface; means for applying the ply means to the substrate surface toproduce the composite structure; and means for curing the compositestructure.
 23. The apparatus of claim 21, further comprising a means fortacking a first end of the ply means to the substrate surface.
 24. Theapparatus of claim 21, further comprising a means for sensing acondition of the applied ply means.
 25. The apparatus of claim 24,further comprising a means for determining whether the applied ply meansis placed within a predetermined location based on the sensing means.26. The apparatus of claim 21, further comprising a means for cuttingthe ply means.